Cytokine signaling through leukemia inhibitory factor receptor (LIFR)/gp130 is known to exert a neurotrophic action in the central nervous system, although the role of this signaling in cerebral ischemia remains unknown. We examined the effect of intracerebral injection of LIF after focal cerebral ischemia in rats. The animals underwent a sham operation (sham group) or middle cerebral artery occlusion (MCAO) followed by direct injection of either vehicle (phosphate-buffered saline, the PBS group) or recombinant LIF (10 ng in the low-LIF group and 100 ng in the high-LIF group) into the cerebral cortex adjacent to the inner boundary zone of the infarct area, and neurologic and histologic evaluations were conducted 24 h later. Expression of LIFR, gp130, and phosphorylated Stat3, Akt, and ERK1/2 was investigated by Western blot analysis and immunohistochemistry. The neurologic deficits and ischemic damage were significantly less severe in the high-LIF group than in the PBS group and the low-LIF group. Leukemia inhibitory factor receptor and gp130 were expressed in neurons, and the ischemic damage of these proteins was rescued in the high-LIF group. Early induction of phosphorylated Stat3 was significantly detected on the ischemic side in the high-LIF group after LIF injection. Exogenous LIF attenuates ischemic brain injury by activating cytokine signaling through LIFR/gp130.
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